High levels of carbon monoxide forced the evacuation of a day care center Friday and sent at least eight adults to hospitals.

Milwaukee Fire Department spokesman Lt. Larry Jenkins said six firefighters and two civilians were taken to St. Luke's Medical Center. He didn't know their conditions but said none of the injuries was life-threatening.

No children were at the day care center at the time, Jenkins said.

Heavenly Day Care was evacuated after someone inside called 911 about 7:30 a.m. to report a person had passed out in the kitchen, said Amanda Lanaghan, a fire department spokeswoman.

"When we came in, the carbon monoxide readings were pretty high," Jenkins said.

He said the potentially deadly gases came from swimming pool heater with a blocked ventilation system, which sent fumes into the building.